Sri Lanka won the final Twenty20 international against South Africa by six wickets in Hambantota on Tuesday to retain their number one ranking in the shortest format.
Sri Lanka put on a spirited chase of South Africa’s commanding 163.3 and won with 11 balls to spare as Tillakaratne Dilshan hit an unbeaten 74 off 51 balls.
South Africa won the series 2-1.
Sri Lanka would have slipped to number three behind Pakistan and South Africa had they been whitewashed 3-0.
Earlier, Du Plessis, who won the toss for the third time in a row and elected to bat, smashed 10 boundaries and three sixes during a third-wicket stand of 112 with J.P. Duminy.
Left-handed Duminy remained unbeaten on a 34-ball 51 (3x4, 2x6).
Scores: South Africa 163/3 (F. Du Plessis 85, J.P. Duminy not out 51) lost to Sri Lanka 164/4 in 18.1 overs (T. Dilshan not out 74, M. Jayawardene 33, Wiese 2/24).